The present invention relates to locking mechanisms in general, and more particularly to a locking mechanism for locking a vehicle hood in its closed position.
Since the advent of the automobile, attempts have been made by persons other than the owner or authorized users to gain access to or possession of the same, either to joyride or to steal the automobile or parts thereof for financial gain. This problem was recognized quite soon after the development of the first automobile, and the manufacturers have attempted to make such unauthorized activity as difficult as possible, if not impossible. So, for instance, it is customary nowadays not only to provide the doors of the car or similar motor vehicle with locks, but also to make the ignition operatable only by a key. Moreover, many cars are provided with burglar alarms to alert the owner or anyone close enough to perceive the alarm of any unlawful or unauthorized entry into the car. However, as the sophistication of such protective devices grew, so did the dexterity and ingenuity of car thieves, while burglary tools became better suited for the intended purposes, so that there is hardly any car on the road which a skilled car thief could not enter and drive away, given sufficient time to accomplish this task. Since it is almost impossible to make a car totally burglar-proof, and since it may even be desirable to keep the possibility of entering the car without the proper set of keys open, for instance, when the owner loses the keys, or when a law enforcement officer, a fireman or another person in a similar position has to enter the car in the absence of the owner or user, such as in the event of an emergency, to discontinue the operation of a malfunctioning burglar alarm or the like, the car manufacturing industry limits itself to installing only such protective devices which will make it very time-consuming to gain access to the car or into the various compartments thereof, but not impossible. The aftermarket manufacturers of protective devices are guided by similar considerations.
Most of the passenger cars currently on the market are provided with a locking or latching arrangement for the vehicle hood which can be partially or fully opened or released by operating a release lever or a similar release actuator situated in the passenger compartment of the car. Thus, a person who has gained access to the passenger compartment, either because the owner forgot to lock the door or after picking the lock or otherwise opening the door locking mechanism, can also rather easily gain access to the motor compartment situated under the hood. Thus, if a burglar alarm is situated in the motor compartment, such a person can discontinue the operation of the same, for instance, by cutting the electric wires supplying electric current thereto. Such a person can also "hotwire" the car, that is, bypass the key-operated ignition switch, and drive away. Also, certain parts, such as the battery or the like, can be stolen from the engine compartment or replaced by lesser quality parts, for instance, in parking garages or parking lots while the owner or authorized user is absent, either by dishonest attendants or by other patrons or persons entering the premises and entering the passenger compartment through an unlocked door while the car is otherwise unattended.
To avoid such possibilities, there have been developed locking or latching arrangements for the vehicle hood of various degrees of complexity. So, for instance, the U.S. Pat. No. 4,099,593 discloses an automobile lock mechanism including a key-operated, cable-displaced cam lock that selectively prevents actuation of the regular hood release mechanism by immobilizing the release cable. The U.S. Pat. No. 3,347,071 illustrates and describes another construction of automobile hood locking mechanism which includes a key-operated latching element coacting with a slotted lever forming a part of the hood latching mechanism for releasably holding the slotted lever against movement. Another latching device for an automobile hood is revealed in U.S. Pat. No. 3,199,322 wherein the latching device is key-operated and is operative for preventing movement of the regular hood latching mechanism. The hood latching device of the U.S. Pat. No. 2,809,064 is cable-operated and is to be used for preventing conventional hood release mechanism actuation. Finally, U.S. Pat. No. 2,756,085 discloses a barrier device for automobile hood locks, wherein the barrier device includes a secondary latch that holds the main hood latch against release until the barrier device is removed by a pull on a flexible cable. Other hood locking devices are shown in U.S. Pat. Nos. 4,102,164, 3,668,908, 1,733,128, 2,693,381, U.S. Pat. No. Re. 16,945, U.S. Pat. Nos. 1,725,158, 1,825,413, 1,481,498 and 1,713,645.
Most if not all of the above-mentioned arrangements are factory-installed and quite incapable of modification so that the expedients used therein can be utilized only if the car has such an arrangement as a part of the original equipment, or upon extensive modification, including replacing the original locking or latching arrangement in its entirety by the new one. To avoid such extensive rebuilding, it was proposed to provide an add-on locking mechanism including an L-shaped locking bracket which has one arm mounted on the underside of the hood by conventional metal screws, and a downwardly extending arm, as well as a slidable piston assembly which is mounted below the locking bracket. The piston assembly includes a slidable piston which is movable between a locking position in which it is received in an oversized hole or slot of the downwardly extending slot, and a retracted position in which the piston is remote from the hole of slot. The piston is movable between its locking and retracted positions by a cable whose end remote from the piston is situated in the passenger compartment of the motor vehicle. In contrast to the conventional hood locking arrangement cable which is connected to a lever or a similar freely actuatable element, the actuating, end of the cable of this add-on locking mechanism is connected to a key-operated lock, such as a Chapman lock. The cable is acutated to move the piston into or out of the oversized hole of the locking bracket by turning the proper key in the lock. The oversized configuration of the hole is necessary in order to assure that the piston will be able to enter the same, regardless of inaccuracies of mounting of the locking bracket and of the piston mechanism, which are unavoidable when the locking mechanism is mounted as an add-on equipment, regardless of the care taken.
Now, many hood holding or locking arrangements are so constructed, especially when the hood opens in front, that the hood release mechanism will permit the hood to open only partially in response to the operation of the hood release lever or the like, so that a gap of a predetermined relatively small width will be formed between the hood and the vehicle body. Then, a safety mechanism which may be accessed through this gap has to be operated before the hood can be fully opened. Because of the oversized configuration of the hole in the locking lever, the add-on or redundant locking mechanism will not interfere with the formation of this gap upon actuation of the release lever, even if the piston is still in its locking position. Thus, an intruder who has gained access to the hood release lever by entering the passenger compartment may operate the hood release lever and then insert a crowbar or a similar lever into the gap and pry the hood open, or render the add-on locking mechanism inoperative, for instance, by deforming the locking bracket through the gap out of the way of the locking piston. This, of course, is very disadvantageous.